You Can Play Team Fortress 2′s Mann vs. Machine Mode Now
The cooperative robot-blasting Horde mode Valve has added to Team Fortress 2 is now available, so go play it.
Like all of TF2, Mann vs. Machine is free to play — for the most part, anyway. You can jump into almost any server and fire up the game with your friends, and playing on those servers will put you on pace to getting timed loot drops to amp up your characters.
There are also special “Mann Co.” servers, where you can play something called Mann Up Mode. In order to do that, you’ll need to acquire “Tour of Duty” tickets, which cost $0.99 each. Doing that lets you earn special rewards along the way, and you’ll get stat-tracking through the various “missions” (read: games that go through multiple maps). You don’t have to pay to play Mann vs. Machine, but you can to get extra stuff.
You can get more information on the mode right here.